At present, low temperature polysilicon (LTPS) has been widely used in the manufacture of display panels. The conventional LTPS technology mainly adopts an excimer laser annealing (ELA) process in which an excimer laser beam is used to illuminate and transform a substrate of amorphous silicon structure into a substrate of polysilicon structure at a high temperature. The polycrystal silicon structure has a more regular arrangement of crystalline grans and a higher mobility of carriers, which helps to improve the reaction speed and driving current of the display panel.
The conventional excimer laser annealing apparatus generally includes a laser source, a carrying platform, etc. A substrate to be annealed is placed on the carrying platform, a laser source is used to emit a laser beam to the substrate, and the laser beam is made to scan various areas of the substrate by controlling linear movement of the carrying platform. In addition, for the same substrate, the platform can be repeatedly moved to allow the same area of the substrate to be repeatedly illuminated multiple times to further optimize the size of the grains.
However, it is difficult to complete the scanning of the entire substrate by one time of linear movement due to limitation of illumination range of the laser beam. Therefore, it is possible to control the platform to move longitudinally to scan part of areas of the substrate, and move laterally to make another area correspond to the laser beam, and then move longitudinally to scan the another area. When the carrying platform moves laterally, the substrate is not within the illumination range of the laser beam and cannot be scanned. Therefore, the time of period for lateral movement belongs to ineffective time which increases the manufacture time for the product. In particular, when the substrate is repeatedly scanned, multiple times of lateral movement will significantly increase the manufacture time.
In should be noted that the information disclosed in this BACKGROUND section is only for an enhanced understanding of the background of the present disclosure, and therefore may contain information which does not constitute the prior art known to those skilled in the art.